Asymmetric reduction methods using microorganisms such as baker's yeast to produce optically active (S)-4-halo-3-hydroxybutyrate ester (Unexamined Published Japanese Patent Application No. (JP-A) Sho 61-146191, JP-A Hei 6-209782, and so on) have been known for some time. These production methods, however, have problems that must be solved for industrial applications because the optical purity and yield of the product are low due to more than one reductases existing in microbial cells. Optically active (S)-4-halo-3-hydroxybutyrate ester is utilized as a synthetic intermediate of drugs. It is thus important in the chemical industry to determine how to produce (synthesize or resolve) optically purified antipodes of the compound.
Enzymes capable of producing (S)-4-halo-3-hydroxybutyrate ester from 4-haloacetoacetate ester are described below, and methods for synthesizing (S)-4-halo-3-hydroxybutyrate ester using these enzymes have been reported.                3-Hydroxysteroid dehydrogenase (JP-A Hei 1-277494)        Glycerol dehydrogenase (Tetrahedron Lett. 29, 2453-2454 (1988))        Alcohol dehydrogenase derived from Pseudomonas sp. PED (J. Org. Chem. 57, 1526-1532 (1992))        Reductases derived from baker's yeast (D-enzyme-1, D-enzyme-2, J. Am. Chem. Soc. 107, 2993-2994 (1985))        Aldehyde dehydrogenase 2 derived from Sporobolomyces salmonicolor (Abstract of 391st Meeting of the Kansai Branch of the Japan Society of Bioscience, Biotechnology, and Agrochemistry, p37 (1995))        Ketopantothenate reductase derived from Candida macedoniensis (Arch. Biochem. Biophys. 294, 469-474 (1992))        Ethyl 4-chloroacetoacetate reductase derived from Geotrichum candidum (Enzyme Microb. Technol. 14, 731-738 (1992))        Carbonyl reductase derived from Candida magnoliae (WO98/35025)        Carbonyl reductase derived from Kluyveromyces lactis (JP-A Hei 11-187869)        
Most of these enzymes are reductases that require reduced nicotinamide adenine dinucleotide phosphate (NADPH) as a coenzyme. Thus, the method for synthesizing (S)-4-halo-3-hydroxybutyrate ester using these enzymes is industrially disadvantageous because it needs the addition and regeneration of expensive and chemically unstable NADPH.
3-Hydroxysteroid dehydrogenase, glycerol dehydrogenase, and alcohol dehydrogenase derived from Pseudomonas sp. PED are oxidoreductases, which catalyze not only reduction reactions using reduced nicotinamide adenine dinucleotide (NADH) as an electron donor but also oxidation (dehydrogenation) reactions. The use of these enzymes cannot produce (S)-4-halo-3-hydroxybutyrate ester in a high yield because the equilibrium of the enzymatic reaction is likely to limit the reaction rate.